# Initial Design of a Self-Retracting Trocar for Distal Ventriculoperitoneal Catheter Insertion

## TL;DR

This paper introduces a new self-retracting trocar designed to safely and effectively insert catheters into the peritoneal cavity during shunt procedures.

## Contribution

The novel self-retracting trocar design is introduced with engineering analyses to ensure performance and safety for distal ventriculoperitoneal catheter insertion.

## Key findings

- FEA confirmed structural integrity with high load capacities for the trocar components.
- The prototype's sharp blade and retractable tip reduced tissue trauma and showed acceptable sharpness performance.
- Testing showed a breakthrough force of 2.98 N, slightly higher than a commercial trocar.

## Abstract

Background

Laparoscopic access, assisted by a general surgeon, is the most commonly used technique for inserting a distal catheter during ventriculoperitoneal shunt placement. This study introduces a novel single-use trocar designed for peritoneal access, combining engineering analyses to ensure performance and safety.

Methods

We presented the design and bench evaluation of this new trocar concept. A Pugh matrix evaluated material and feature optimization, while failure mode and effect analysis (FMEA) identified risks such as blade dulling and spring failure. Finite element analysis (FEA) confirmed the structural integrity of the trocar.

Results

The FEA confirmed the structural integrity of the trocar, demonstrating high load capacities of 1655.3 N for the shaft, 503.4 N for the cannula, and 2799.12 N for the handle with minimal deformation and a high safety margin. The prototype features a sharp blade with an automatically retractable blunt tip to reduce tissue trauma and a cannula with a side slit for catheter insertion. Using sausage casing to simulate the peritoneum, sharpness testing showed a breakthrough force of 2.98 N compared to 2 N for the Versastep trocar (Medtronic, Minneapolis, MN).

Conclusions

The assessment and conceptualization of this new trocar showed reliability, a low risk of component failure, and good sharpness performance after multiple laboratory tests. The self-retractable tip provides a safety profile during insertion into the peritoneal cavity. Further testing in vivo is needed.